Field of the Invention
The present invention relates to a solid-state imaging device, an imaging device, and a signal reading method.
Description of the Related Art
Recently, video cameras, electronic still cameras, and the like have been widely used. Charge coupled device (CCD) type or amplification type solid-state imaging devices are used in such cameras. An amplification type solid-state imaging device guides signal charges, which have been generated and stored in a photoelectric conversion portion of a pixel on which light is incident, to an amplification portion disposed in the pixel and outputs a signal, which has been amplified by the amplification portion, from the pixel. In the amplification type solid-state imaging device, such pixels are arranged in a two-dimensional matrix shape. An example of the amplification type solid-state imaging device is a complementary metal oxide semiconductor (CMOS) type solid-state imaging device using a CMOS transistor.
In the related art, a general CMOS type solid-state imaging device employs a method of sequentially reading signal charges, which have been generated by photoelectric conversion portions of pixels arranged in a two-dimensional matrix shape, for each row. In this method, since an exposing timing in the photoelectric conversion portion of each pixel is determined depending on reading start and end of the signal charges, the exposing timing differs for each row. Accordingly, when a rapidly moving subject is imaged using the CMOS type solid-state imaging device, the subject in the captured image is deformed.
In order to remove the deformation of a subject, a simultaneous imaging function (global shutter function) of realizing synchronous storage of signal charges has been proposed. Uses of the CMOS type solid-state imaging device having the global shutter function are becoming various. In order to store signal charges generated by the photoelectric conversion portions until the signal charges are read, the CMOS type solid-state imaging device having the global shutter function generally needs to have a storage capacitor portion having a light-blocking property. In such a CMOS type solid-state imaging device according to the related art, all of the pixels are simultaneously exposed, then signal charges generated by the photoelectric conversion portions are simultaneously transferred from all of the pixels to the storage capacitor portions and are temporarily stored therein, and the signal charges are sequentially converted into pixel signals at a predetermined reading timing and are read.
However, in the CMOS type solid-state imaging device according to the related art having the global shutter function, the photoelectric conversion portions and the storage capacitor portions have to be formed in the same plane of the same substrate and thus an increase in chip area is inevitable. In a waiting period of time until the signal charges stored in the storage capacitor portions are read, signal quality is degraded by noise due to light or noise due to a leak current (dark current) generated in the storage capacitor portions.
A solid-state imaging device in which a MOS image sensor chip in which micro pads are formed on a wiring layer side for each unit cell and a signal processing chip in which micro pads are formed on a wiring layer side at positions corresponding to the micro pads of the MOS image sensor chip are connected to each other by micro bumps is disclosed in Japanese Unexamined Patent Application, First Publication No. 2006-49361. A method of preventing an increase in chip area using a solid-state imaging device in which a first substrate on which photoelectric conversion portions are formed and a second substrate on which a plurality of MOS transistors are formed are bonded to each other is disclosed in Japanese Unexamined Patent Application, First Publication No. 2010-219339.